Spring Boot打包JAR后MySQL驱动类识别失败问题求助

问题场景 #

本地Eclipse中运行Spring Boot应用完全正常，但通过Maven导出JAR后启动时抛出如下错误：

Failed to determine a suitable driver class

完整异常信息：

Error creating bean with name 'dataSource' defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceConfiguration$Hikari.class]: Failed to instantiate [com.zaxxer.hikari.HikariDataSource]: Factory method 'dataSource' threw exception with message: Failed to determine a suitable driver class

现有配置 #

pom.xml 核心配置 #

<dependencies>      
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>        
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.27</version>
</dependency>        
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>        
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>
</dependencies>
<build>
<plugins>                   
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-assembly-plugin</artifactId>
    <configuration>                         
        <descriptorRefs>
            <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>        
        <archive>
            <manifest>                                  
                <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
                <addClasspath>true</addClasspath>
                <mainClass>com.biswajit.RDSExample</mainClass>
            </manifest> 
        </archive>
    </configuration>
    <executions>
        <execution>
            <id>make-assembly</id>
            <phase>package</phase>
            <goals>
                <goal>single</goal>
            </goals>
        </execution>
    </executions>
</plugin>
</plugins>
</build>

application.properties 配置 #

spring.jpa.hibernate.ddl-auto=create-drop
spring.jpa.generate-ddl=true
spring.jpa.show-sql=true
spring.datasource.url=jdbc:mysql://database-2.**..amazonaws.com:3306/mydb
spring.datasource.username=admin
spring.datasource.password=*****
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

解决方法 #

1. 替换Maven打包插件（核心修复） #

问题出在使用了maven-assembly-plugin打包，这个插件的打包逻辑和Spring Boot的可执行JAR规范不兼容——Spring Boot需要特定的类加载器结构来加载依赖，而assembly插件只是简单把所有依赖打包到一个JAR，会导致驱动类无法被正确识别。

移除maven-assembly-plugin，改用Spring Boot官方提供的spring-boot-maven-plugin，修改后的build部分如下：

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <mainClass>com.biswajit.RDSExample</mainClass>
            </configuration>
            <executions>
                <execution>
                    <goals>
                        <goal>repackage</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

2. 优化MySQL驱动依赖（可选） #

可以去掉MySQL驱动的手动版本号，让Spring Boot的依赖管理自动适配兼容版本，避免版本冲突：

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <!-- 移除手动version，由Spring Boot parent管理 -->
    <scope>runtime</scope> <!-- 可选，明确驱动仅在运行时需要 -->
</dependency>

3. 重新打包并启动 #

执行以下Maven命令完成打包：

mvn clean package

然后运行生成的可执行JAR（注意替换为实际的JAR文件名）：

java -jar target/RDSExample-xxx.jar

内容的提问来源于stack exchange，提问作者Biswajit Tah